1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58aluminium Determination of specific surface area by nitrogen adsorptionICS 71.100.10Aluminium oxide
2、 primarily used for the production of BRITISH STANDARDBS ISO 8008:2005BS ISO 8008:2005This British Standard was published under the authority of the Standards Policy and Strategy Committee on 23 January 2006 BSI 23 January 2006ISBN 0 580 47298 1Cross-referencesThe British Standards which implement i
3、nternational publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online.This publication does not purport to in
4、clude all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations.Summary of pagesThis document comprises a front cover, an inside front cover, the ISO title page, pages ii
5、 to v, a blank page, pages 1 to 7 and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Date CommentsA list of organizations represented on this committee can be obtained on request to its secretar
6、y. present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK.National forewordThis British Standard reproduces verbati
7、m ISO 8008:2005 and implements it as the UK national standard. It supersedes BS 4140-23:1987 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee CII/24, Raw materials for the aluminium industry, which has the responsibility to: aid enquirers to understand
8、the text;INTERNATIONALSTANDARDISO8008Second edition2005-10-15Reference numberISO 8008:2005(E)Aluminium oxide primarily used for the production of aluminium Determination of specific surface area by nitrogen adsorptionOxyde daluminium principalement utilis pour la production de laluminium Dterminatio
9、n de la surface spcifique par adsorption dazoteBS ISO 8008:2005iiiiiContents Page1 Scope 12 Normative references 13 Principle 14 Reagents . 15 Apparatus . 26 Sampling and sample preparation . 27 Procedure . 38 Calculation and reporting of results 49 Precision . 410 Quality control 411 Test report 4A
10、nnex A (informative) Difference between single- and multi-point-determined BET SSA 6Annex B (informative) Results of test programme 7BS ISO 8008:2005ivForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies(ISO member bodies). The work
11、of preparing International Standards is normally carried out through ISOtechnical committees. Each member body interested in a subject for which a technical committee has beenestablished has the right to be represented on that committee. International organizations, governmental andnon-governmental,
12、 in liaison with ISO, also take part in the work. ISO collaborates closely with the InternationalElectrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task
13、 of technical committees is to prepare International Standards. Draft International Standardsadopted by the technical committees are circulated to the member bodies for voting. Publication as anInternational Standard requires approval by at least 75 % of the member bodies casting a vote.Attention is
14、 drawn to the possibility that some of the elements of this document may be the subject of patentrights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 8008 was prepared by Technical Committee ISO/TC 226, Materials for the production of primaryaluminium.This seco
15、nd edition cancels and replaces the first edition (ISO 8008:1986), which has been technically revised.BS ISO 8008:2005vIntroductionThis International Standard is based on Australian Standard AS 2879.4-2003, Alumina Determination ofspecific surface area by nitrogen adsorption.BS ISO 8008:2005viblank1
16、Aluminium oxide primarily used for the production of aluminium Determination of specific surface area by nitrogen adsorptionWARNING Persons using this International Standard should be familiar with normal laboratorypractice. This International Standard does not purport to address all of the safety p
17、roblems, if any,associated with its use. It is the responsibility of the user to establish appropriate safety and healthpractices and to ensure compliance with any national regulatory conditions.1ScopeThis International Standard specifies an instrumental method for the determination of specific surf
18、ace area(SSA) of smelter-grade alumina (SGA) by nitrogen adsorption by a single- or multi-point method. A multi-pointmethod is recommended due to the higher accuracy obtained; if a single-point method is used, a lower resultwill be obtained.NOTE Annex A provides an explanation of the difference betw
19、een single- and multi-point determined BET SSA.This International Standard is applicable to aluminas having a surface area between and .2 Normative referencesThe following referenced documents are indispensable for the application of this document. For datedreferences, only the edition cited applies
20、. For undated references, the latest edition of the referenced document(including any amendments) applies.AS 2850-1986, Chemical analysis Interlaboratory test programs For determining precision of analyticalmethod(s) Guide to the planning and conduct3 PrincipleThe method is based on the ability of a
21、 material to adsorb nitrogen molecules on its surface at the boiling pointof liquid nitrogen. The instrument determines the quantity of nitrogen gas necessary to form a monolayer of gasmolecules on the sample surface. The surface area can then be calculated using the basic theory developed byBrunaue
22、r-Emmett-Teller1). A test sample is degassed at . The degassing process can be carried outusing either vacuum or a flowing nitrogen stream. After degassing, the sample is weighed. This mass, and themonolayer volume determined by the instrument, is used to calculate the specific surface area.4Reagent
23、sUse only reagents of recognized analytical grade and only distilled water or water of equivalent purity.1) S. Brunauer, P.H. Emmett and E. Teller, J. Am Chem. Soc. 60, p.309 (1938).50 m2/g 90 m2/g150CBS ISO 8008:200524.1 Liquid nitrogen, with a boiling point of at 2).CAUTION Particular care should
24、be taken when handling cryogenic liquids.4.2 Nitrogen gas, high purity.4.3 Other gases, as specified by the instrument manufacturers.4.4 Reference aluminaAlcan International Limited3)Alumina Surface Area Standard ALU-114): which is a commercial product sold byAlcan International Limited as part of t
25、heir in-house commitment to supply reference materials to thealumina/aluminium industry. The certified value at confidence level of ALU-11 for single-point analysis isand for multi-point analysis is .NOTE Annex A provides an explanation of the difference between single- and multi-point determined BE
26、T SSA.5 Apparatus5.1 Surface-area analyser, employing low temperature ( ) nitrogen adsorption. The instrumentshould be capable of multi-point or single-point analysis.5.2 Degassing equipment, suitable for degassing a sample at an elevated temperature ( ) using eithera flowing nitrogen stream or a va
27、cuum system capable of maintaining a vacuum of .Sample tubes shall include sealing devices to prevent contact between air and the sample after degassing.5.3 Analytical balance, capable of weighing to an accuracy of .6 Sampling and sample preparationA test sample is prepared from the laboratory sampl
28、e using a riffle or a rotary divider, taking particular careto avoid loss of fine particles through dusting. A representative test portion of optimum mass (depending on therequirements of the instrument and anticipated surface area) shall be taken from the test sample. The mass ofsample used should
29、be such that the total surface area is in accordance with the recommendations of themanufacturer of the surface-area analyser (5.1) and with a minimum sample mass of .Clean all sample tubes prior to each batch of samples analysed. It is recommended that the tubes be cleanedin an ultrasonic bath. To
30、speed up the drying process, it is recommended that the tubes be rinsed with ethanolbefore being put into the drying oven.2) . The unit atm is deprecated.3) Alcan International Limited,Arvida Ris the mass of sample tube, sealing device and test sample after degassing, in grams;is the mass of degasse
31、d test sample, in grams.g) Using sample mass ( ), and the procedures recommended by the instrument manufacturer, determinethe specific surface area of the test sample. Record the specific surface area reported by the instrument, tothe nearest .150CP/Po0,162 nm2Po0,000 1 g m1150C2h0,000 1 g m2m3=m2m1
32、m1m2m3m30,01 m2/gBS ISO 8008:200548 Calculation and reporting of resultsIf the instrument reports only the total surface area, calculate the specific surface area of the test sample by:whereis the specific surface area of the test sample, in square metres per gram;is the total surface area of the te
33、st sample, in square metres, reported by the instrument;is the mass of degassed test sample, in grams.Record the calculated specific surface area to the nearest .Report the specific surface area thus calculated, or the specific surface area recorded in 7.2 g) to the nearestwhole unit.9PrecisionA tes
34、t programme of the method in this International Standard was carried out in accordance with AS 2850.From the results of this programme, a within-laboratory repeatability ( ) and between-laboratory reproducibility( ), at the confidence level as given in Table 1, should be achieved.The results of the
35、test programme are given in Annex B.10 Quality controlThe specific surface area of the reference alumina (4.4) shall be determined for every batch of samples, byrepeating the procedure in 7.2 and substituting the test sample with the reference material.If this result does not lie between for single-
36、point determinations, or for multi-point determinations, then it shall be noted in the test report along with the certified value.11 Test reportThe test report shall contain the following information:a) reference to this International Standard, i.e. ISO 8008;b) identification of the sample;c) date o
37、n which the sample was taken;Table 1 Precision data for specific-surface-area determinationsDeterminationRepeatability () Reproducibility ()m2/g m2/gSingle-point 0,8 2,1Multi-point 1,0 2,5ASSA=Sm3ASSASm30,01 m2/grR 95 %rR67,82,9 m2/g 69,12,3 m2/gBS ISO 8008:20055d) date on which the test was carried
38、 out;e) specific surface area of the test sample, expressed in square metres per gram, to the nearest whole unit;f) whether the analysis was single-point or multi-point;g) information in accordance with Clause 10, if required;h) any unusual observations made during the course of the test which may h
39、ave had an effect on the result.BS ISO 8008:20056Annex A(informative)Difference between single- and multi-point-determined BET SSADifferences between single- and multi-point SSA for SGA are typically between and . The single-point solution of the BET equation is a simplification of the theory which
40、results in a lower SSA than the multi-point solution. This difference can be calculated provided the constant is known for the material beinganalysed. The constant in the BET equation is a term that relates to the energy of interaction between thesurface and the adsorbate. For the single-point solut
41、ion, the assumption is made that is large (greater than100) resulting in terms in the BET equation simplifying. The BET-plot intercept goes to zero and the slope isinversely proportional to the monolayer volume. This simplification enables the BET equation to be solved bymeasuring the volume of adso
42、rbate at a single partial pressure.The difference arising from the assumptions applied in the single-point formulation is:whereis the partial pressure used in the single-point measurement;is the adsorbate/surface-interaction energy term determined in the multi-point equation.For smelter grade alumin
43、as, is typically between 100 and 200.Hence for and , the difference is at the level. This equates to the single-pointanalysis being lower than the multi-point analysis.1m2/g 3 m2/gCCCRelative percentage difference=1001Cx/Cx+(1x)xCCC=150 x=0,3 1,5 % 70 m2/g1,1 m2/gBS ISO 8008:20057Annex B(informative
44、)Results of test programmeA test programme of the method in this International Standard was carried out in accordance with AS 2850.Samples of the Alcan ALU-11 reference material and two other samples from different refineries were analysed.Results were provided in quadruplicate by eleven, nine and s
45、ix laboratories respectively for samples ALU-11,ALU-10 and S-119. The within-laboratory ( ) and between-laboratory ( ) precision data (at confidencelimits) and mean-specific-surface-area determinations calculated from the results are given in Table B.1.From these results, an absolute repeatability o
46、f 0,8 and an absolute reproducibility of 2,1 should be achieved forsingle-point determinations, and similarly 1,0 and 2,5 for multi-point determinations.Table B.1 Precision data for specific-surface-area determinationsTest samplesSpecific surface area(mean value)Repeatability () Reproducibility ()m2
47、/g m2/g m2/gsp mp sp mp sp mpALU-11 67,8 69,1 0,8 1,2 2,9 2,3ALU-10 52,9 54,1 0,4 0,6 1,1 3,1S-119 85,0 88,1 1,1 1,1 2,0 2,0rR95 %rRBS ISO 8008:2005BS ISO BSI389 Chiswick High RoadLondonW4 4AL8008:2005BSI British Standards InstitutionBSI is the independent national body responsible for preparing Bri
48、tish Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter.RevisionsBritish Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions.It is th
49、e constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: +44 (0)20 8996 9000. Fax: +44 (0)20 8996 7400.BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards.B
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